This invention relates to security devices and to systems incorporating such devices, and is especially applicable to security devices in the form of portable secure objects and associated systems.
The term portable secure object is well known and commonly used by those skilled in the art, to indicate a small portable object such as a credit card or smart card or a smart electronic key, which contains personal, commercial or other information in analog digital form which a user wishes to remain secure, usually from use or access by unauthorized persons.
This invention is particularly applicable to arrangements using smart cards such as are described in the co-pending International patent application No. PCT/GB97/01451 but may be applied to other systems using any card or other portable secure object containing information which needs to be accessed by means of an acoustic, electrical, electronic, mechanical or vibrational transducer.
In the arrangement described in patent application No. PCT/GB97/01451 an acoustic interface is provided to enable a person in possession of a smart card to input a voice signal as a biometric feature to a card reader machine into which the card has been inserted in order to confirm the identity of the speaker and thus permit access by the speaker to the information on the card or in the system to which the card is inserted or otherwise applied. In such systems the voice biometric data may be coded appropriately and stored on the card or in some centralized store for retrieval and comparison.
JP-A-63-292287 (Abstract) discloses a similar arrangement which records a voiceprint of a card owner and stores the coded voiceprint on a card, and for identifying the card owner during later use of the card, the system records a voiceprint of the user and makes a comparison with the voiceprint stored on the card.
It is has been found that a major problem in embodying and using such systems is that the characteristics of input microphones or other input transducers vary significantly, such that the sound patterns generated and stored during registration may not match the sound patterns produced by the individual during interrogation, even if the subject speaker spoke his or her input phrase in an identical fashion. Microphone and transducer variability therefore is a major adverse feature of such systems which prevents or precludes their widespread use.
It is an object of the present invention to provide an improved system whereby the problem related to microphone variability is substantially overcome.
According to the present invention there is provided a security system comprising in combination a portable secure object and a terminal for use with said object, said portable secure object including means for storing information, and means for storing a coded sound signal or a signal indicative thereof, microphone means being provided, and means responsive to said microphone means for generating said coded sound signal during a registration procedure, characterised in that said microphone means is formed integrally with said portable secure object, and in that an output derived from said microphone means is connected to said terminal, whereby said microphone means is subsequently used for deriving in said terminal a further coded sound signal for comparison with said generated coded sound signal for subsequent interrogation purposes.
The feature of embodying a microphone on a smart card is known from DE-U-9316734, but the same microphone is not used to deliver the generated sound signal to the system terminal.
In one arrangement for carrying out the invention it is arranged that said terminal comprises sound transmission means for transmitting a sound signal input to said terminal to the microphone means of said portable secure object, signal processing means responsive to an electrical signal from said microphone means for generating a coded signal indicative of said sound signal, and means for applying a signal to said portable secure object corresponding to said coded signal.
In another arrangement for carrying out the invention it is arranged that said terminal comprises sound transmission means for transmitting a sound signal input to said terminal to the microphone means of said portable secure object, signal processing means responsive to an electrical signal from said microphone means for generating a coded signal indicative of said sound signal, means responsive to a signal stored in said portable secure object for generating a coded sound signal, comparison means for comparing the generated coded sound signal with the coded sound signal generated by said processing means and for permitting access to the confidential information stored on said portable security device in dependence upon the correspondence therebetween.
In a preferred system said signal processing means comprises a plurality N of signal comparators, each signal comparator being adapted to compare the electrical signal from said microphone means with a plurality of different exemplar signals and for affording an output indicative of which of said exemplar signals corresponds most closely to said electrical signal, the sets of exemplar signals of each of said signal comparators being different, said electrical signal being input to each of said signal comparators to derive an N-part coded signal which is indicative of said sound signal. Advantageously each of said signal comparators will be based on time encoded signal processing and recognition (TESPAR) coding.
In carrying out the invention it may be arranged that said coded sound signal is stored in said portable secure object or alternatively is stored remotely from said portable secure object.
Preferably, the said portable secure object takes the form of a magnetic stripe swipe card, an electronic smart card, or a plastic card having bar coded information thereon.